To analyze the clinical presentation of perineal endometriosis and evaluate its treatment.Clinical data were analyzed from the records of 36 patients with perineal endometriosis who were operated on between 1983 and 2007 at Peking Union Medical College Hospital, and followed up for 0.5 to 14 years.The incidence of perineal endometriosis was 0.31% among the women with endometriosis treated surgically at the hospital. The latent period was between 4 months and 13 years. All patients had cyclical and painful lesions. Of the 36 patients, 5 (13.9%) also suffered from pelvic endometriosis. All patients without anal sphincter involvement were cured after complete surgical excision. In 7 patients who had anal sphincter involvement, disease recurred because of incomplete excision.Perineal endometriosis can be diagnosed on the basis of clinical features and surgical excision is the treatment of choice. The recurrence rate of perineal endometriosis is related to sphincter involvement making preoperative evaluation of anal sphincter important.